Cooling of cable sheaths, particularly aluminium cable sheaths



Feb. 4, 1964 w. LINNERZ 3,120,305

COOLING 0F CABLE SHEATHS, PARTICULARLY ALUMINIUM CABLE SHEATHS Filed May '7. 1959 2 Sheets-Sheet 1 FIG. I

All, bZZZZfiI'Z Feb. 4, 1964 w. LINNERZ 3,120,305

COOLING OF CABLE SHEATHS, PARTICULARLY ALUMINIUM CABLE SHEATHS United States Patent Ofitice Patented Feb. l, 1964' 3,126,395 CGQLING F CABLE SHEATHS, PARTICULARLY ALUMINIUM CABLE SHEATHS Wilhelm Linnerz, Dusseldorf-Ellen Germany, assignor to Schloemann Aktiengeseilschaft, Dusseldorf, Germany Filed May 7, 1959, Ser. No. 811,747 Claims priority, application Germany May 17, 195% 2 Claims. (Q1. 2l71) It is necessary, in the production of cable sheaths, particularly those made of aluminium, to cool the sheath, in order to obviate any injury to the insulation of the cable owing to an excessive action of great heat. On the other hand, during the halt ng times which are necessary in the course of the extrusion operation as a whole for the purpose of re-clrarging the press with a fresh heated aluminium billet, too great a cooling of the cable sheath is to be avoided, so as to prevent the formation of re-crystallised spots in the cable sheath, as these would exhibit less strength and elasticity than the rest of the sheath.

The object of the present invention is to provide a method and apparatus which will ensure not only an adequate cooling of the cable sheath during the extrusion operation but also an appropriate maintenance of the temperature during the halting times.

According to the invention, during the halting times of the extrusion operation, air, preferably heated air, is

lown on to the cable sheath instead of water. \By blowing air on to it, particularly preheated air, during the halting times, a slighter cooling of the cable sheath is effected, which can be so adjusted that the cable sheath does not reach too high a temperature, such as might destroy the cable insulation, but on the other hand is not so far cooled that the cable sheath withdraws too much heat from the extrusion material located in the extrusion chamber.

Apparatus for carrying out the method comprises a double tube for supplying the water, this double tube surrounding the sheathed cable as it issues from the press. The inner tube of the double tube is provided with nozzles for the discharge of the cooling fluid, a valve member being provided for opening and closing alternately the supply of air and water to the double tube.

One constructional example of the invention is illustrated in the accompanying drawings, in which:

FIGURE 1 shows in horizontal section the main parts of a hydraulic press; while FIGURE 2 shows, on a larger scale, a longitudinal section through the cooling apparatus of the press head.

The actual press head 2 of the press is stationarily supported, in a manner known in itself, upon a machine foundation. From both sides a container 4 is pressed, likewise in a known manner, by means not illustrated, against the press head 2. Each container 4 has a sleeve 6, which is designed for the reception of the heated metal billet, of aluminium for example.

In each sleeve there is a press disc 8, which can be impelled towards the press head 2 by a press ram 10. The actuation of the rams is preferably efiected, in a manner known in itself, by hydraulic means, namely by means of stationary cylinders, in each of which there moves a piston, which actuates the ram 10. The press head 2 has in its longitudinal direction a bore, which is differentially constructed. It accommodates at the top a screw member 12, which is screwed into the press head 2 by means of a thread 13, and presses an annular flange of the mandrel-holder 14 against a shoulder 15 in the press-head bore. The mandrel-holder 14 carries the mandrel 16. From the other side a screw member 18 is screwed into the press head 2 by means of a thread 19. The screw member 18 presses the die-holder 22, which carries the die 24-, against a shoulder 23. The mandrel 16 and the die 24 are therefore firmly held in the press head 2. From one side a cable 26 is passed through the screw member 12 into and through the longitudinal bore in the head 2. It is sheathed with aluminium in the gap between the mandrel i6 and the die 24, so that a sheath 2?) is formed. The two press discs 3 are moved forward at the same time, so that the extrusion material 3% which is distinguished by cross-hatching, is forced through passages 31, and the so-called extrusion chamber 32, to form the sheath 28.

Into the screw member 18 and the die-holder 22 a double tube 34, 35 is inserted, which forms, with the internal wall surface of the screw member 18, an annular space 36, which is in communication with the atmosphere. The annular space 38 of the double tube 34, 35 is connected by way of a pipe 42 with a reciprocable valve 40, here shown as a piston valve, which supplies to it either water or air. Water is supplied to the valve 40 under pressure through a duct 43, and air, likewise under pressure, through a duct 44. The valve member 46 can be brought into one position or the other, against the action of a spring 48, by -a magnet St).

The water or air is sprayed through nozzles 52 on to the cable sheath 2%, obliquely to the direction or" motion of the cable 26, and is discharged through the annular space 54 between the inner tube 34 and the sheath itself. During the halting times the valve 4% is reversed, so that air is supplied through the pipe 42 to the annular space 33, and this air is blown through the nozzles 52 on to the cable sheath 2%, thereby obviating an excessive cooling or the cable sheath 25, or of the material to be extruded which is still located in the extrusion chamber 32. The controlling of the valve 40 may of course be effected in dependence upon the cessation of the extrusion pressure in the press cylinders actuating the press narns ll).

1 claim:

1. in the sheathing of an electric cable with aluminum in which the aluminum is intermittently extruded between the mandrel and die of an extrusion press, a method of cooling the newly formed aluminum cable sheath, said method including the steps of directing jets of cooling water against the aluminum sheath as the aluminum sheath leaves the die during extrusion and discontinuing the jets of water and directing jets of air against the aluminum sheath during periods when extrusion is suspended and the aluminum sheath is at rest, whereby the formation of recrystallized spots in the aluminum sheath is prevented.

2. A method of cooling a newly formed extruded aluminum cable sheath as defined in claim 1, in which the jets of air are heated prior to contact with the aluminum.

References Qited in the file of this patent UNITED STATES PATENTS 408,377 Cobb Aug. 6, 1889 1,983,761 Jacob-son Dec. 11, 1934 2,161,570 Harris June 6, 1939 2,863,557 -Mun.ker Dec. 9, 1958 2,950,816 Arenz Aug. 30, 1960 FOREIGN PATENTS 448,585 Canada May 18, 1948 718,077 Great Britain Nov. 10, 1954 770,871 Great Britain Mar. 27, 1957 657,959 Great Britain Oct. 3, 1957 

1. IN THE SHEATHING OF AN ELECTRIC CABLE WITH ALUMINUM IN WHICH THE ALUMINUM IS INTERMITTENTLY EXTRUDED BETWEEN THE MANDREL AND DIE OF AN EXTRUSION PRESS, A METHOD OF COOLING THE NEWLY FORMED ALUMINUM CALE SHEATH, SAID METHOD INCLUDING THE STEPS OF DEIRECTING JETS OF COOLING WATER AGAINST THE ALUMINUM SHEATH AS THE ALUMINUM SHEATH LEAVES THE DIE DURING EXTRUSION AND DISCONTINUING THE JETS OF WATER AND DIRECTING JETS OF AIR AGAINST THE ALUMINUM SHEATH DURING PERIODS WHEN EXTRUSION IS SUSPENDED AND THE ALUMINUM SHEATH IS AT REST, WHEREBY THE FORMA- 